This invention relates to power distribution systems and, more particularly, to a multichannel power distribution system for individually controlling power to a plurality of loads.
A variety of systems have been proposed for controlling the distribution of power to individual loads, particularly in large vehicular systems, such as aircraft. When each load is controlled and/or protected by a separate, stand-alone apparatus, the distribution of power is conceptually simple, but suffers from certain operational disadvantages. Such systems are highly redundant, for example, and do not permit any great degree of coordination or adaptability. For these reasons, attempts have been made to implement more sophisticated control schemes.
Before power to a large number of loads can be distributed by a single integrated system, however, individual power switching devices must be isolated electrically from any common control or "logic" stage. Unfortunately, the limited bandwidths and nonlinear characteristics of conventional isolation circuitry present serious operational problems in the context of a power distribution system. For example, conventional optocouplers in conjunction with voltage-to-frequency converters operate well only within a relatively limited range of approximately four kilohertz to approximately twenty kilohertz, and the output of an optocoupler can normally be decoded only by counting the digital pulses of the output itself. This causes the decoding process, and therefore the reaction time of any associated electronic control, to be very slow.
Prior power distribution systems have also required power switching devices of different designs for each different power rating. A large number of spare parts must then be stocked over the life of the system, complicating both manufacture and installation.
Therefore, it is desirable in many applications to provide a power distribution system and method which isolates any control logic from switching elements without interfering with the efficient communication of status information and commands between different components of the system. It is also desirable to reduce the cost of manufacturing and maintaining such a system.